a) Field of the Invention
The present invention relates to a golf club including a hollow head formed by joining a plurality of metallic shells together and a shaft connected to one side of the head.
b) Prior Art
Whilst metallic golf clubs with hollow head structure have been widely used, it is desirable for a ball striking portion to develop a larger repulsive force against balls in order to elongate the traveling distance of balls. To realize such lager repulsive force, the thickness of a face member serving as a ball striking portion may be thinned to thereby enlarge the deflection of the face member at the time of striking a ball. This, however, causes a problem that the thinned face member will have lowered durability.
Conventional solutions for solving the above-mentioned problem are disclosed in Japanese Un-Examined Patent Publication Nos.11-114105, 11-244428, 2001-58015 and 2001-62004, all of which disclose multi-layered face, enlarging the repulsive force by thinning the face member while improving the durability thereof. However, when a conventional golf club is tested after it is manufactured by thinning a face and superimposing a metal plate on a surface of the face only, it has been revealed that although the repulsive force is surely enhanced, there is a practical problem in respect of durability as the superimposed metal plate has turned out to come off due to only 500 times strikes of balls
After careful study of any cause of the above problem, it has been revealed that whilst the multi-layered face member according to conventional art can surely enhance the repulsive force against balls by thinning each metal plate which constructs the face member, but a portion of the metal plate that is joined to an outline of the face surface is likely to become fragile tissue, depending on how firmly it is joined by welding or the like. In that case, shocks caused by the repeated strikes of balls will urge the metal plate to come off from the joined portion, so that the joined portion will be destructed easily. Although the durability can be surely improved by joining the metal plate to the face portion at a ball striking portion by means of welding or the like, it would then make no difference from the face member formed from a single thick plate, and no improvement of durability would be able to be expected.
To eliminate the above-mentioned problems, it is, therefore, a main object of the present invention to provide a golf club with improved durability of a face ember against the repeated strikes of balls as well as improved repulsive force against balls developed in the ball striking portion.
To attain the above object, there is provided, in accordance with a first aspect of the invention, a golf club including a head and a shaft connected to one side of the head, said head including a hollow body formed by combining a plurality of metallic shells inclusive of a face member which is provided with a ball-striking portion on a front, wherein said face member is made up of a plurality of metallic plates which are superimposed over an entire surface thereof, each of said metallic plates having an outer peripheral edge extended rearwardly to define an extended portion, said extended portion having a rear end portion joined to a rear shell which constructs a rear part of said head.
Accordingly, a repulsive force of the ball-striking portion against balls can be improved by making each of the face-member-constructing metallic plates thinner and more flexible. Further, the durability of the face member can be improved by extending rearwardly the outer periphery of the metallic plates which construct the face member, as the impacts caused by the repeated strikes of balls are allowed to be transmitted to the rear shell of the head, without being directed to the direction to make the metallic plates separate from each other.
A golf club according to a second aspect of the invention is a golf club of the first aspect, wherein said plurality of metallic plates which construct said face member are not mutually joined at least in said ball-striking portion.
Accordingly, as the plurality of metallic plates which construct the face member are effectively bent in the ball-striking portion, the repulsive force of the ball-striking portion against balls can be improved.
A golf club according to a third aspect of the invention is a golf club of any of the foregoing aspects, wherein the thickness of said ball-striking portion is less than 3.0 mm, while said extended portion is thinner than said ball-striking portion.
By making the ball-striking portion relatively thick, the durability of the face member against the repeated strikes of balls can be improved.